- Boolean session_start( )
Initializes a session by either creating a new session or using an identified one. Checks for the variable
$PHPSESSIDin the HTTP request. If a session identifier isn't included in the request, or an identified session isn't found, a new session is created. If a session ID is included in the request, and a session isn't found, a new session is created with the
PHPSESSIDencoded in the request. When an existing session is found, the session variables are read from the session store and initialized. Using PHP's default settings, a new session is created as a file in the /tmp directory. This function always returns
- string session_id([string
Can be used in two ways: to return the ID of an initialized session and to set the value of a session ID before a session is created. When used to return the session ID, the function must be called without arguments after a session has been initialized. When used to set the value of the session ID, the function must be called with the ID as the parameter before the session has been initialized.
- Boolean session_register(mixed
name[, mixed ...])
Registers one or more variables in the session store. Each argument is the name of a variable, or an array of variable names, not the variable itself. Once a variable is registered, it becomes available to any script that identifies that session. This function calls the
session_start( )code internally if a session has not been initialized. The
session_unregister( )function is called to remove a variable from the session. Returns
truewhen the variables are successfully registered.
- Boolean session_is_registered(string
trueif the named variable has been registered with the current session and
falseotherwise. Using this function to test if a variable is registered is a useful way to determine if a script has created a new session or initialized an existing one.
Unregisters a variable with the initialized session. Like the
session_register( )function, the argument is the name of the variable, not the variable itself. Unlike the
session_register( )function, the session needs to be initialized before calling this function. Once a variable has been removed from a session with this call, it is no longer available to other scripts that initialize the session. However, the variable is still available to the rest of the script that calls
- session_unset( )
Unsets the values of all session variables. This function doesn't unregister the actual session variables. A call to
session_is_registered( )still returns
truefor the session variables that have been unset.
- Boolean session_destroy( )
Removes the session from the PHP session management. With PHP's default settings, a call to this function removes the session file from the /tmp directory. Returns
trueif the session is successfully destroyed and
In this section we list the key functions used to build session-based applications in PHP. Greater control over sessions can be achieved through the configuration of PHP-as we discuss in the Section 8.3.8 section-or by using
GET variables to encode the session ID, as discussed in the next section.